U.S. patent application number 15/928640 was filed with the patent office on 2018-10-11 for multi-ply knit fabric.
The applicant listed for this patent is Milliken & Company. Invention is credited to Emily W. Michaels, Robert D. Miller, Rajib Mondal, James A. Rogers, Petr Valenta, Thomas C. Wiles.
Application Number | 20180290425 15/928640 |
Document ID | / |
Family ID | 61913641 |
Filed Date | 2018-10-11 |
United States Patent
Application |
20180290425 |
Kind Code |
A1 |
Mondal; Rajib ; et
al. |
October 11, 2018 |
MULTI-PLY KNIT FABRIC
Abstract
A multi-ply knit fabric containing a first knit ply and a second
knit ply. The first knit ply contains a plurality of first yarns
and forms the upper surface of the fabric. The second knit ply
forms the lower surface of the fabric and contains a plurality of
polytetrafluoroethylene (PTFE) yarns having a density of about 2 to
2.25 g/cm.sup.3, a transmission in the IR region of 8-10 .mu.m at
least about 60%, and a thermal conductivity of at least about 0.2
W/(m.K). The plies are integrated through combined portions formed
by at least one of the following methods: interlacing first yarns
among the PTFE yarns of the second knit ply, interlacing PTFE yarns
among the first yarns of the first knit ply, and interlacing a
plurality of third yarns among the first yarns of the first knit
ply and the PTFE yarns of the second knit ply.
Inventors: |
Mondal; Rajib; (Greer,
SC) ; Wiles; Thomas C.; (Easley, SC) ;
Michaels; Emily W.; (Taylors, SC) ; Valenta;
Petr; (Greer, SC) ; Miller; Robert D.;
(Piedmont, SC) ; Rogers; James A.; (Greenville,
SC) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Milliken & Company |
Spartanburg |
SC |
US |
|
|
Family ID: |
61913641 |
Appl. No.: |
15/928640 |
Filed: |
March 22, 2018 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
62481927 |
Apr 5, 2017 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
D04B 1/16 20130101; D04B
1/24 20130101; B32B 5/06 20130101; B32B 5/026 20130101; D10B
2403/0114 20130101; D10B 2321/042 20130101; D04B 21/207 20130101;
B32B 5/26 20130101; D04B 21/16 20130101 |
International
Class: |
B32B 5/06 20060101
B32B005/06; D04B 1/24 20060101 D04B001/24; D04B 1/16 20060101
D04B001/16; D04B 21/20 20060101 D04B021/20; D04B 21/16 20060101
D04B021/16; B32B 5/02 20060101 B32B005/02; B32B 5/26 20060101
B32B005/26 |
Claims
1. A multi-ply knit fabric having an upper and lower surface,
wherein the fabric comprises: a first knit ply comprising a
plurality of first yarns, wherein the first knit ply forms the
upper surface of the fabric; a second knit ply comprising a
plurality of polytetrafluoroethylene (PTFE) yarns, wherein the PTFE
yarns have a density of about 2 to 2.3 g/cm.sup.3, a transmission
in the IR region of 8-10 .mu.m at least about 40%, and a thermal
conductivity of at least about 0.2 W/(m.K), wherein the second knit
ply forms the lower surface of the fabric; wherein the first ply
and the second ply integrated through combined portions formed by
at least one method selected from the group consisting of
interlacing first yarns among the PTFE yarns of the second knit
ply, interlacing PTFE yarns among the first yarns of the first knit
ply, and interlacing a plurality of third yarns among the first
yarns of the first knit ply and the PTFE yarns of the second knit
ply.
2. The multi-layer knit fabric of claim 1, wherein the PTFE yarns
have a generally rectangular cross-sectional shape.
3. The multi-layer knit fabric of claim 1, wherein the fabric
comprises less than about 75% by weight PTFE yarns.
4. The multi-layer knit fabric of claim 1, wherein the fabric
comprises less than about 50% by weight PTFE yarns.
5. The multi-layer knit fabric of claim 1, wherein the second knit
ply comprises at least about 90% by weight PTFE yarns.
6. The multi-layer knit fabric of claim 1, wherein the PTFE yarns
comprise a density of about 2.15 to 2.25 g/cm.sup.3.
7. The multi-layer knit fabric of claim 1, wherein the PTFE yarns
comprise a transmission in the IR region of 8-10 .mu.m at least
about 60%.
8. The multi-layer knit fabric of claim 1, wherein the PTFE yarns
comprise a thermal conductivity of at least about 0.23 W/(m.K).
9. The multi-layer knit fabric of claim 1, wherein the rectangular
cross-sectional shape of the PTFE yarns has a width to height ratio
of between about 20:1 to 100:1.
10. The multi-layer knit fabric of claim 1, wherein the lower
surface of the fabric has a surface roughness of less than about
500 .mu.m.
11. An article of clothing comprising the fabric of claim 1
12. An article of clothing comprising a multi-ply knit fabric
having an upper and lower surface, wherein the fabric is oriented
such that the lower surface of the fabric faces the wearer of the
article of clothing, wherein the fabric comprises: an first knit
ply comprising a plurality of first yarns, wherein the first knit
ply forms the upper surface of the fabric; a second knit ply
comprising a plurality of polytetrafluoroethylene (PTFE) yarns,
wherein the PTFE yarns have a density of about 2 to 2.3 g/cm.sup.3
a transmission in the IR region of 8-10 .mu.m at least about 40%,
and a thermal conductivity of at least about 0.2 W/(m.K), and
wherein the second knit ply forms the lower surface of the fabric;
wherein the first ply and the second ply integrated through
combined portions formed by at least one method consisting of
interlacing first yarns among the PTFE yarns of the second knit
ply, interlacing PTFE yarns among the first yarns of the first knit
ply, and interlacing a plurality of third yarns among the first
yarns of the first knit ply and the PTFE yarns of the second knit
ply.
13. The article of clothing of claim 12, wherein the PTFE yarns
have a generally rectangular cross-sectional shape.
14. The article of clothing of claim 12, wherein the fabric
comprises less than about 50% by weight PTFE yarns.
15. The article of clothing of claim 12, wherein the second knit
ply comprises at least about 90% by weight PTFE yarns.
16. The article of clothing of claim 12, wherein the PTFE yarns
comprise a transmission in the IR region of 8-10 .mu.m at least
about 60%.
17. The article of clothing of claim 12, wherein the PTFE yarns
comprise a thermal conductivity of at least about 0.23 W/(m.K).
18. The article of clothing of claim 12, wherein the article of
clothing is worn directly in contact with the wearer's skin.
19. The article of clothing of claim 12, with in the article of
clothing is selected from the group consisting of a shirt, pair
pants, tights, jacket, socks, and undergarments.
20. The article of clothing of claim 12, wherein the lower surface
of the fabric has a surface roughness of less than about 500 .mu.m.
Description
RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional Patent
Application 62/481,927, filed on Apr. 5, 2017, which is herein
incorporated by reference in its entirety.
TECHNICAL FIELD OF THE INVENTION
[0002] The present invention is directed multi-ply knit fabrics,
more particularly to multi-ply knit fabrics where one of the plies
contains polytetrafluoroethylene (PTFE) yarns.
BACKGROUND
[0003] A fabric that is cool to touch and the cooling that is
activated by air flow is highly desirable for wearer in the warmer
environment or a performance/sportswear. In addition to performance
wear, such fabric will find application in varieties of textile
application. A desirable fabric would be an infrared-transparent
visible-opaque fabric (ITVOF), which utilizes the human body's
innate ability to thermally radiate heat as a cooling mechanism.
Thus there is a need for a cooling textile.
BRIEF SUMMARY OF THE INVENTION
[0004] A multi-ply knit fabric having an upper and lower surface,
wherein the fabric contains a first knit ply and a second knit ply.
The first knit ply contains a plurality of first yarns and forms
the upper surface of the fabric. The second knit ply contains a
plurality of polytetrafluoroethylene (PTFE) yarns, where the PTFE
yarns have a density of about 2 to 2.3 g/cm.sup.3, a transmission
in the IR region of 8-10 .mu.m at least about 40%, and a thermal
conductivity of at least about 0.2 W/(m.K). The second knit ply
forms the lower surface of the fabric and if the fabric is formed
into an article of clothing, would be the surface of the fabric
adjacent the wearer. The first ply and the second ply are
integrated through combined portions formed by at least one method
selected from the group consisting of interlacing first yarns among
the PTFE yarns of the second knit ply, interlacing PTFE yarns among
the first yarns of the first knit ply, and interlacing a plurality
of third yarns among the first yarns of the first knit ply and the
PTFE yarns of the second knit ply.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] FIG. 1 is an illustration of a cross-section of the
multi-ply knit fabric according to one embodiment of the
invention.
[0006] FIG. 2 is a is a photo-micrograph of a cross-section of the
multi-ply knit fabric according to one embodiment of the
invention.
[0007] FIG. 3 is a photomicrograph of the upper surface of the
multi-ply knit fabric of FIG. 2.
[0008] FIG. 4 is a photomicrograph of the lower surface of the
multi-ply knit fabric of FIG. 2.
[0009] FIG. 5 is a photomicrograph of some PTFE yarns in the knit
fabric.
[0010] FIG. 6 is a knit diagram of the multi-ply knit fabric
according to one embodiment of the invention.
DETAILED DESCRIPTION
[0011] The challenge is developing a textile that is transparent to
IR where human body radiates but opaque to visible light. Most
textile materials (cotton, polyester, nylon etc) strongly absorb
human body radiation and have very low IR transparency. Polyolefins
such as polyethylene (PE), polypropylene (PP),
polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF) have
only aliphatic C--C, C--H, and C--F bonds and have narrow
absorption peaks centered at the wavelengths of 3.4, 3.5, 6.8, 7.3,
and 13.7 .mu.m, which are all far away from the peak of human body
radiation. It would be ideal to create a fabric in which the face
has the ability to block the radiation from outside and the back
(surface next to skin) has the ability to bring the radiative heat
close to the outer surface of the fabric to dissipate into the
environment through convection. In addition, if the back of the
fabric (next to skin) has high thermal conductivity, the fabric
will be able to distribute the thermal energy from the body
throughout the surface of the fabric more efficiently to take
advantage of the greater surface area. Since vaporization is the
primary mechanism of heat loss from the body at higher temp
(>30.degree. C.), hydrophobic back and hydrophilic face will
lead to good pumping of moisture from the skin to the environment.
PTFE has almost 10.times. higher thermal conductivity or lower
thermal resistance than polyester, cotton or other typical textile
materials. PTFE is transparent in the IR region where human body
emits. It is also hydrophobic and has very low friction
co-efficient, which are beneficial for the wearer in terms of
comfort.
[0012] Human body is typically warmer than the environment. Thus
facilitating the heat transfer from the human body to the fabric
will lead to more efficient heat loss from body to the environment.
Greater heat loss contributes to the better performance for
application of cooling fabric. Contact area is one of the most
important determinant of how warm or cool a fabric feels to an
individual. A smoother and flat surface increases the area of
contact and the heat transfer, thereby will create a fabric with
greater cooling efficiency.
[0013] Referring now to FIG. 1, there is shown an illustration of a
cross-section of one embodiment of the multi-ply knit fabric 10.
The knit fabric 10 has an upper surface 10a and a lower surface
10b. When the fabric 10 is made into a garment, preferably the
lower surface 10b would be facing the wearer and upper surface 10a
would be facing away from the wearer. The knit fabric 10 of FIG. 1
is shown containing 2 plies; a first knit ply 100 and a second knit
ply 200. The knit fabric 10 is a unitary material that is formed
together in a knitting machine with the two plies separated by a
dashed line. The plies 100 and 200 are not formed as discrete knit
layers and then joined together in a later operation. FIG. 2 is a
photomicrograph of a cross-section of one embodiment of the
multi-ply knit fabric 10. FIG. 3 is a photomicrograph of the upper
surface (first knit ply) of the multi-ply knit fabric of FIG. 2 and
FIG. 4 is a photomicrograph of the lower surface (second knit ply)
of the multi-ply knit fabric of FIG. 2.
[0014] The multi-ply knit fabric 10 may be made by any suitable
knitting method, including both warp knitting and weft (or
circular) knitting. Circular knitting is preferred in some
embodiments, as it tends to be more cost efficient. The two plies
may have the same knit construction or different.
[0015] The first knit ply 100 comprising a plurality of first yarns
and forms the upper surface 10a of the fabric 10. The first yarns
in the first knit ply 100 may be any suitable yarn. "Yarn", in this
application, as used herein includes a monofilament elongated body,
a multifilament elongated body, ribbon, strip, yarn, tape, fiber
and the like. The first knit ply 100 may contain one type of yarn
or a plurality of any one or combination of the above. The yarns
may be of any suitable form such as spun staple yarn, monofilament,
or multifilament, single component, bi-component, or
multi-component, and have any suitable cross-section shape such as
circular, multi-lobal, square or rectangular (tape), and oval. In
one preferred embodiment, the first ply 100 contains multifilament
polyester yarns as these have been shown to have good performance
at low cost.
[0016] The first knit ply may have any suitable knit pattern and be
formed by any suitable yarns. The yarns in the first ply may be a
single plurality or type of yarn (e.g., the fabric can be formed
solely from yarns comprising a blend of cellulosic yarns and
synthetic yarns, such as polyamide yarns), or the textile can be
formed from several pluralities or different types of yarns (e.g.,
the fabric can be formed from a first plurality of yarns comprising
cellulosic yarns and polyamide yarns and a second plurality of
yarns comprising an inherent flame resistant yarn). The yarns may
be formed of (but are not limited to) cellulosic yarns (such as
cotton, rayon, linen, jute, hemp, cellulose acetate, and
combinations, mixtures, or blends thereof), polyester yarns (e.g.,
poly(ethylene terephthalate) yarns, poly(propylene terephthalate)
(PET) yarns, poly(trimethylene terephthalate) yarns), poly(butylene
terephthalate) yarns, and blends thereof), polyamide yarns (e.g.,
nylon 6 yarns, nylon 6,6 yarns, nylon 4,6 yarns, and nylon 12
yarns), polyvinyl alcohol yarns, an elastic polyester-polyurethane
copolymer (SPANDEX.RTM.), flame-resistant meta-aramid (NOMEX.RTM.)
and combinations, mixtures, or blends thereof.
[0017] The second knit ply 200 comprising a plurality of
polytetrafluoroethylene (PTFE) yarns and forms the lower surface
10b of the fabric 10. Preferably, if the fabric 10 is made into a
garment, the second knit ply 200 faces the wearer and is preferably
in direct contact with the wearer's skin. The lower surface 10b of
the fabric 10 has a surface roughness of less than about 500 .mu.m,
preferably less than about 200 .mu.m. PTFE yarn could be of any
denier or sizes. In one preferred embodiment, 220 denier PTFE is
used and in another embodiment, 100 denier PTFE yarn is used.
However, depending on the desired weight (oz per sq. yd) and other
properties, the denier of the PTFE yarn could be smaller or
larger.
[0018] The PTFE yarns have a density of about 2 to 2.5 g/cm.sup.3,
more preferably about 2.0 to 2.3 g/cm.sup.3, more preferably about
2.15 to 2.25 g/cm.sup.3. Typical textile yarns, such polyester,
nylon or cotton have density less than 1.6 g/cm.sup.3. The PTFE
yarns have a transmission in the IR region of 8-10 .mu.m at least
about 40%, more preferably at least about 60%. In case of
polyester, it has C--O stretching frequency from 7.7-10 micron and
C--H bending from 7.8-14.5 micron, which leads to reduced
transmission, 20% or less in the IR region of 8-10 micron. I has
been shown that this 20% of less transmission in the IR region of
8-10 microns produces a fabric with less active cooling. The PTFE
yarns also have a thermal conductivity of at least about 0.2
W/(m.K), more preferably at least about 0.23 W/(m.K), more
preferably at least about 0.25 W/(m.K). Polyester yarn has much
lower thermal conductivity of .about.0.15 W/(m.K). Preferably, the
PTFE yarns have a generally rectangular cross-sectional shape.
[0019] When measuring aspect ratio, the cross-section of the yarn
is measured across the entire width (even if the tape is folded
onto itself). In one embodiment, the PTFE yarns have a
cross-section aspect ratio across the entire width of between about
20:1 to 100:1. Typical flat polyester has the aspect ratio of less
than 5:1. Typical PTFE yarn is used in a folded state, meaning that
there are fold lines running along the length of the tape yarns and
portions of the yarn lay on other portions of the yarn (sometimes
like an accordion) such as can be seen in FIG. 5. If the aspect
ratio is measured of the folded PTFE yarn, the aspect ratio would
be between about 10:1 to 2:1.
[0020] The first 100 and second 200 plies are integrated through
combined portions, this is preferably done at the time of knitting
such that the fabric 10 is created as a multi-ply knit fabric, not
as two separate knit fabrics that are then joined in a subsequent
process step. This integration may be from one of the following
methods, or a combination of the methods.
[0021] The first method is interlacing first yarns from the first
ply among the PTFE yarns of the second knit ply, meaning that a
portion of the first yarns from the first ply leave the first ply,
travel down into the second ply where they are interlaced with
yarns within the second ply, and then travel back up to the first
ply.
[0022] The second method is interlacing PTFE yarns from the second
ply among the first yarns of the first knit ply, meaning that a
portion of the PTFE yarns from the second ply leave the second ply,
travel up into the first ply where they are interlaced with yarns
within the first ply, and then travel back down to the second ply
to the first ply.
[0023] The third method is interlacing a plurality of third yarns
among the first yarns of the first knit ply and the PTFE yarns of
the second knit ply. This means that a third yarn (which may be the
same or different yarn than the first yarns and/or PTFE) travels
between the plies, interlacing with yarns from both plies and in
essence, tying them together. Preferably, the third yarns comprise
PTFE yarns.
[0024] In a preferred embodiment, the second method is used to
interlace the first 100 and second 200 ply together. This method is
preferred because of the lower complexity during the knitting
process using the circular knitting.
[0025] In one embodiment, the multi-ply knit fabric is made using
what is referred to as a flat back mesh construction. In this
construction, the yarns are evenly spaced on the flat side, while
the yarns are not spaced evenly on the mesh side (PTFE side)
(open). The knitting diagram for this construction can be seen in
FIG. 6. Preferably, the second ply is more open than the first ply,
meaning that there are gaps in the second ply (so that when looking
at the lower surface of the fabric 10, some of the first ply 100
can be seen through the gaps in the second ply 200. The mesh allows
the moisture from the human skin to transport more efficiently to
the environment, while minimizing the materials use. PTFE is
preferably used in the mesh side. In the mesh side, the gaps
between two yarn could be up to 0.5-1 mm.
[0026] Thickness of the both faces are almost equally distributed,
while contents of different yarns are controlled by changing the
gap between the yarns in the mesh side. Tightness of the knitting
is also controlled to achieve the total fabric thickness. Typical
fabric thickness can be varied from 0.25-0.8 mm.
[0027] In one embodiment, the fabric 10 contains a third knit
layer. Preferably, this third knit layer is on the first ply (on
the side opposite to the second ply) or between the first and
second plies. When the fabric 10 contains a third ply, the second
play preferably still forms the lower surface 10b of the fabric 10.
The third layer may be knitted from any of the materials (or
combinations of materials) disclosed as suitable materials for the
first 100 or second 200 ply and is preferably knit as the same time
and integral with the first and second plies.
[0028] It is preferred to have the amount of PTFE yarns in the
fabric 10 (as a whole) be as low as possible due to the cost of the
PTFE yarns in relation to the other yarns in the fabric 10. In one
embodiment, the fabric 10 comprises less than about 75% by weight
PTFE yarns. In another embodiment, the fabric 10 comprises less
than about 50% by weight PTFE yarns. In another embodiment, the
fabric 10 comprises between about 5 and 75% by weight PTFE yarns.
It is believed to be most important to concentrate the PTFE yarns
on the lower surface 10b of the fabric 10 to maximize their cooling
effect for the wearer of the fabric 10. In one embodiment, the
second knit ply comprises at least about 90% by weight PTFE yarns.
In another embodiment, the lower surface 10b comprises at least
about 90% by weight PTFE yarns.
[0029] In one embodiment, the multi-ply knit fabric is made into an
article of clothing. The article of clothing is preferably made
such that the lower surface 10b (second ply 200) faces the wearer
and forms the innermost surface of the article of clothing.
[0030] This article of clothing may be any suitable article but is
preferably an article of clothing that is worn next to the wearer
(so preferably a shirt versus a coat). The mechanisms of the
cooling work more efficiently when the article of clothing is in
direct contact with the skin of the wearer. The article of clothing
could be, for example, a short, pair of pants, tights, jacket,
socks, hat, or undergarments.
[0031] In another embodiment, a garment may use the multi-layer
knit fabric in addition to other fabric. For example, a shirt might
use the multi-layer knit fabric on the torso and another fabric in
the sleeves. Additionally, the multi-layer knit fabric could also
be used as an insert.
Test Methods
[0032] Weight of the fabric was measured using ASTM D 3776. Air
permeability was measured using ASTM D 737. MVTR was measured ASTM
E 96-95: Water Vapor Transmission of Materials, modified procedure
B; both Open Jar Method and with the Air Flow method. Q-Max is the
measurement of the maximum heat loss that can occur when the skin
touching objects or other materials. Larger Q-max, cooler the
material, in this case fabric, to human touch. The Kawabata thermal
tester (Thermolabo) is used to measure the Q-max. Intrinsic thermal
resistance, apparent intrinsic evaporative resistance, and total
heat loss are measured using a sweating guarded hot plate using
ASTM F1868, Part C.
EXAMPLES
[0033] The table below summarizes the 13 examples. The PTFE yarn
used was either 220 den (Lenzing.TM. Profilen FG02 natural) and 100
den (Lenzing.TM. Profilen FR110 natural). The polyester yarn used
was a multi-filament yarns in a 1 ply or 2 ply 70/72 construction.
Examples 1-8 were knitted in flat back mesh construction as shown
in FIG. 6. Example 9 was a 50/50 PTFE (220 den)/polyester interlock
knit and example 10 was a 100% polyester interlock knit. Examples
1-10 were subjected to navy disperse dyeing process and tentering
for testing and evaluation. Example 11 was a commercially available
fabric from ADIDAS.TM. called Climachil which is a double knit,
bi-ply. The outerply contains typical multifilament round polyester
yarn and the inner ply contains multifilament flat polyester
yarns.
TABLE-US-00001 Polyester PTFE Ounces per square Yarn content yarn
type yarn type yard (OSY) oz/yd.sup.2 Ex. 1 69%/31% 1/70/72 220 den
5.7 PTFE/polyester Ex. 2 53%/47% 2/70/72 220 den 8.8 PTFE/polyester
Ex. 3 36%/64% 2/70/72 100 den 6.0 PTFE/polyester Ex. 4 54%/46%
1/70/72 100 den 3.7 PTFE/polyester Ex. 5 77%/23% 1/70/72 220 den
5.5 PTFE/polyester Ex. 6 62%/38% 2/70/72 220 den 7.8 PTFE/polyester
Ex. 7 45%/55% 2/70/72 100 den 5.6 PTFE/polyester Ex. 8 63%/37%
1/70/72 100 den 3.3 PTFE/polyester Ex. 9 50%/50% 1/70/72 220 den
6.8 PTFE/polyester Ex. 10 100% Polyester 1/70/72 -- 4.9 and 2/70/72
Ex. 11 See description -- -- 4.2 above
[0034] The examples were tested for air permeability, moisture
vapor transmission rate (MVTR) (ASTM E 96-95: Water Vapor
Transmission of Materials, modified procedure B; both Open Jar
Method and with the Air Flow) (g/m.sup.2/24 hrs) and Q-max
(watts/cm.sup.2) of back (skin side) and face of the fabrics.
TABLE-US-00002 MVTR MVTR (Air Q-max Q-max air perm (Open Jar) Flow)
(back) (face) (cfm) g/m.sup.2/24 hrs g/m.sup.2/24 hrs
watts/cm.sup.2 watts/cm.sup.2 Ex. 1 320 882.37 6090 0.213 0.114 Ex.
2 206 879.53 2.5 0.134 2 Ex. 3 235 862.51 0.187 0.128 Ex. 4 403
876.70 0.167 0.113 Ex. 5 406 848.33 6169 0.214 0.108 Ex. 6 227
845.49 0.215 0.117 Ex. 7 270 913.58 5888 0.169 0.118 Ex. 8 466
842.65 0.154 0.104 Ex. 9 127 868.19 2205 0.165 0.106 Ex. 10 140
811.44 2374 0.122 0.118 Ex. 11 202 713.95 0.155 0.111
[0035] As one can see form the table above, examples containing
PTFE yarn (Examples 1-9) has slightly higher MVTR (.about.840-900
g/m.sup.2/24 hrs) than the polyester examples (Examples 10-11)
(.about.700-800 g/m.sup.2/24 hrs). Comparing Examples 1, 5, and 7
(knitted with the flat back mesh construction as shown in FIG. 3)
had much higher MVTR values in the military method, where there is
airflow at the top of the jar compared to Examples 10 and 13
(without the PTFE yarns). This indicates the moisture vapor
transmission is induced by the airflow.
[0036] In terms of cooling effect, the higher the Q-max, cooler the
fabric feels to its touch. The Q-max measurement using Kawabata
thermal tester (Thermo Labo) showed higher Q-max values on both
sides of the fabric of Examples 1-9 compared to Examples 10-11.
TABLE-US-00003 Intrinsic Apparent Thermal intrinsic Total
resistance evaporative Thermal Heat (R.sub.cf) resistance
Resistance loss Sample (.DELTA. .degree. C.) (R.sub.ef) (I.sub.t)
(Qt) Thickness ID (m.sup.2)/W (.DELTA.kPa)(m.sup.2)/W Clo W/m.sup.2
mm Ex. 1 0.004 0.00206 0.492 869.36 0.42 Ex. 2 0.006 0.00264 0.506
798.26 0.57 Ex. 3 0.007 0.00247 0.509 812.34 0.5 Ex. 4 0.007
0.00098 0.512 1008.92 0.35 Ex. 5 0.004 0.00137 0.493 959.05 0.41
Ex. 6 0.006 0.00228 0.502 837.11 0.57 Ex. 7 0.006 0.0018 0.504
891.68 0.45 Ex. 8 0.004 0.00107 0.491 1009.41 0.31 Ex. 9 0.01
0.00181 0.532 871.17 0.62 Ex. 10 0.009 0.00235 0.525 814.05
0.62
[0037] Total heat loss was measured using a large sweating guarded
hot plate as per ASTM F1868 part C and data is summarized in the
table above. This measurement confirmed that intrinsic thermal
resistance of PTFE yarn based knits with flat back mesh
construction fabric (Ex. 1-8) is lower compared to all polyester
fabrics (Ex. 10). The evaporative resistance of PTFE containing
knits (Ex. 1-8) are lower compared to the all polyester knit (Ex.
10). Lower thermal resistance along with lower evaporative together
yielded fabrics with impressive up to 25% improvement in the total
heat loss, comparing Ex. 1-8 with Ex. 10.
[0038] In conclusion, excellent Q-max, excellent thermal
conductivity (lower resistance), lower evaporative resistance,
higher heat loss for PTFE based flat back mesh knits (Examples
1-8). All these properties are important for active cooling
application in textile.
[0039] All references, including publications, patent applications,
and patents, cited herein are hereby incorporated by reference to
the same extent as if each reference were individually and
specifically indicated to be incorporated by reference and were set
forth in its entirety herein.
[0040] The use of the terms "a" and "an" and "the" and similar
referents in the context of describing the subject matter of this
application (especially in the context of the following claims) are
to be construed to cover both the singular and the plural, unless
otherwise indicated herein or clearly contradicted by context. The
terms "comprising," "having," "including," and "containing" are to
be construed as open-ended terms (i.e., meaning "including, but not
limited to,") unless otherwise noted. Recitation of ranges of
values herein are merely intended to serve as a shorthand method of
referring individually to each separate value falling within the
range, unless otherwise indicated herein, and each separate value
is incorporated into the specification as if it were individually
recited herein. All methods described herein can be performed in
any suitable order unless otherwise indicated herein or otherwise
clearly contradicted by context. The use of any and all examples,
or exemplary language (e.g., "such as") provided herein, is
intended merely to better illuminate the subject matter of the
application and does not pose a limitation on the scope of the
subject matter unless otherwise claimed. No language in the
specification should be construed as indicating any non-claimed
element as essential to the practice of the subject matter
described herein.
[0041] Preferred embodiments of the subject matter of this
application are described herein, including the best mode known to
the inventors for carrying out the claimed subject matter.
Variations of those preferred embodiments may become apparent to
those of ordinary skill in the art upon reading the foregoing
description. The inventors expect skilled artisans to employ such
variations as appropriate, and the inventors intend for the subject
matter described herein to be practiced otherwise than as
specifically described herein. Accordingly, this disclosure
includes all modifications and equivalents of the subject matter
recited in the claims appended hereto as permitted by applicable
law. Moreover, any combination of the above-described elements in
all possible variations thereof is encompassed by the present
disclosure unless otherwise indicated herein or otherwise clearly
contradicted by context.
* * * * *